July 7, 2019  |  

Coexistence of blaOXA-48 and truncated blaNDM-1 on different plasmids in a Klebsiella pneumoniae isolate in China.

Objectives: To describe the genetic environment, transferability, and antibiotic susceptibility of one clinical Klebsiella pneumoniae isolate harboring both blaOXA-48 and blaNDM-1 on different plasmids from a Chinese hospital. Methods: The isolate was subjected to antimicrobial susceptibility testing and multilocus sequence typing using Etest and PCR. The plasmids harboring blaOXA-48 and blaNDM-1 were analyzed through conjugation experiments, S1-nuclease pulsed-field gel electrophoresis, and hybridization with specific probes. Plasmid DNA was sequenced using Pacbio RS II and annotated using RAST. Results:K. pneumoniae RJ119, carrying both blaOXA-48 and blaNDM-1, was resistant to almost all carbapenems, cephalosporins, fluoroquinolone, and aminoglycosides and belonged to ST307. blaOXA-48 was located on a 61,748-bp IncL/M conjugative plasmid, which displayed overall nucleotide identity (99%) to pKPN-E1-Nr.7. blaNDM-1 was located on a 335,317-bp conjugative plasmid, which was a fusion of a blaNDM-1-harboring InA/C plasmid pNDM-US (140,825 bp, 99% identity) and an IncFIB plasmid pKPN-c22 (178,563 bp, 99% identity). The transconjugant RJ119-1 harboring blaNDM-1 was susceptible to carbapenem, and there was an insertion of IS10 into the blaNDM-1 gene. Conclusion: This is the first report of the coexistence of blaOXA-48 and blaNDM-1 in one K. pneumoniae clinical isolate in China. OXA-48 in RJ119 contributed to the majority to its high resistance to carbapenems, whereas NDM-1 remained unexpressed, most likely due to the insertion of IS10. Our results provide new insight for the relationship between genetic diagnosis and clinical treatment. They also indicate that increased surveillance of blaOXA-48 is urgently needed in China.


July 7, 2019  |  

Complete genome sequence of Lysinibacillus sphaericus LMG 22257, a strain with ureolytic activity inducing calcium carbonate precipitation.

Microbiologically induced calcium carbonate precipitation shows the potential for use in bioremediation and construction consolidation, but the efficiency of this process must be improved. Lysinibacillus sphaericus LMG 22257 is a gram-positive ureolytic strain that has recently been applied for consolidating construction by mediating calcium carbonate precipitation. The complete genome sequence of L. sphaericus LMG 22257 is 3,436,578 base pairs with a GC content of 38.99%. The urea degradation pathway and genes related to extracellular polymeric substance biosynthesis were also identified. The strain can tolerate high alkalinity (pH up to 10) and high urea concentration (up to 3M). These findings provide insights into the microbiologically induced carbonate precipitation and extend the application of the metabolic potential of L. sphaericus LMG 22257 for bioremediation. Copyright © 2017 Elsevier B.V. All rights reserved.


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